Arthritis is a common chronic disease, which leads to joint pain due to the degeneration of joint cartilage or the inflammation of connective tissue, and further influences the normal movement of the joint. According to the position and cause of the occurrence, arthritis can be classified into more than one-hundred types. The most common types include osteoarthritis (degenerative arthritis), rheumatoid arthritis (RA), gouty arthritis, bacterial arthritis, ankylosing spondylitis, lupus erythmatosus, etc.
Generally, in the treatment of arthritis, a conservative, non-surgical treatment is initially adopted. When the initial treatment is ineffective, a surgical treatment is then applied. The initial treatment includes drug therapy and injection therapy. In drug therapy, steroidal and non-steroidal anti-inflammatory agents are used. Although the pain-relieving effect of the steroidal agents is prompt and obvious, they may cause many side effects, such as osteoporosis, uncicatrized wounds, upper gastrointestinal bleeding, and may even aggravate existing conditions, such as hypertension, diabetes, etc. Thus, steroidal agents are currently used only in certain limited condition. As for non-steroidal agents, although they also have good pain-relieving activity, if used for a long-term period, side effects like peptic ulcer, lower limb hydrops, impairment of kidney function, etc., may arise. Hence, non-steroidal agents are restricted in practical application.
Hyaluronic acid injections have been broadly used in the treatment of osteoarthritis, in which an injection solution containing hyaluronic acid is directly injected into the joint to moderately alleviate inflammation and pain of patients. Although the mechanism of hyaluronic acid is still unclear, it is known that hyaluronic acid can serve as a lubricant to assist the joint movement and meanwhile improve the joint function. However, although hyaluronic acid may efficiently alleviate pain, it causes transient inflammatory reactions within two days to one week after entering the human body, and even leads to chronic inflammation (see Leopold et al., Increased frequency of acute local reaction to intra-articular hylan GF-20 (Synvisc) in patients receiving more than one course of treatment. J Bone Joint Surg, 2002; 84: 1619-23; Bernardeau et al Acute arthritis after intra-articular hyaluronate injection: onset of effusions without crystal. Ann Rheum Dis, 2001; 60:518-20; and Kroesen et al., Induction of an acute attack of calcium pyrophosphate dihydrate arthritis by intra-articular injection of hylan G-F 20 (Synvisc). Clin Rheumatol, 2000; 19:147-9, which are incorporated hereinto by reference). Thus, the anti-inflammation effect of the hyaluronic acid formulation products in the current market is not ideal.
A method for improving the hyaluronic acid formulation has been disclosed (see Homma et al., Novel hyaluronic acid-methotrexate conjugates for osteoarthritis treatment, Bioorganic and Medicinal Chemistry, 17 (2009), 4647-4656, which is incorporated hereinto by reference). In this method, hyaluronic acid is linked to methotrexate (MTX) with anti-inflammation activity via a polypeptide to form a conjugate using a chemical synthesis approach, and the resultant product has an improved anti-inflammation effect. Nevertheless, according to the disclosure of this document, a mixture formed by simply mixing hyaluronic acid and MTX cannot provide the improving effect; in other words, the synthesis of the conjugate is necessary. However, the preparation of the conjugate needs the use of polypeptide materials and involves complicated synthesis steps, which must increase the cost for manufacturing a hyaluronic acid formulation. Thus, this method not only has difficulties in mass production, but also increases the economic burden of users, and is quite limited in the clinical application. Therefore, there is still a need in the market for a medicament or method that can efficiently improve the anti-inflammation activity of hyaluronic acid and is also simple and convenient in terms of the manufacturing process.
The present invention is a research achievement for the above demand. The inventors of the present invention found that a composition prepared by mixing a 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase inhibitor and hyaluronic acid may inhibit the transient inflammatory reactions caused by hyaluronic acid, and further improve the anti-inflammation effect of hyaluronic acid.